Object ‘Application’¶

Symbol:

The object “Application” is presented as a node in the device tree. It comprises objects required for an executable control program.

You can insert an application object below a PLC Logic node, that is below a programmable device, or as a child application below an already existing application object (parent application).

Below each application there must be a Task Configuration, where you define which program of the application will be called by which task, using which settings.

Additionally, below an application you insert the modules of your control program, for example POUs, global variables lists, library manager. These modules will be only available for this application and its child applications.

Additionally the application may use instances of project-global modules. Project-global modules are managed in the POUs view. Using instances of such modules follows the thinking of object-oriented programming.

Below a PLC Logic device object you can insert multiple applications. They must have unique names.

If there are multiple applications directly below a device object, you must define which application shall be responsible for the I/O-handling of the device. CODESYS will use the variables of this application for the communication with the target system. Set the application in tab PLC Settings of the device editor .

The application to be currently used for online mode operations, must be set “active”; see App2 in the figure shown above.

You can set special properties for an application in the Application build options tab of the Properties dialog. For example: Activation of dynamic memory allocation.

When downloading the application to the PLC, you can add information on the application content. Again this is to be activated in the Application build options tab. Then you will be able later to compare the application on the PLC with the application currently active in CODESYS.

If you want to add application-specific information on author, version and an application-specific short description, then modify the common Project Information entries, using the Information tab of the application Properties dialog.

When you are going to log in to the target system (PLC or simulation) with an application, CODESYS first will check, which applications are currently on the PLC and whether the application parameters on the target match those of the project configuration. Appropriate messages will tell you about mismatches and possible proceedings. During this step you also may remove applications from the PLC.

In the Applications tab of the device editor you can see, which applications are currently available on the device. In this tab you can remove applications from the target system. Possibly the list also shows applications, which are not represented by a separate object in the device tree, like for example <Application>_symbols.app. This application contains a symbol list created for the application (see on “Symbol Configuration”).

See also

• Device Tree and Device Editor
• Object ‘Task Configuration’
• Dialog ‘Properties’ - ‘Application build options’
• Transferring Applications to the PLC
• Tab ‘PLC settings’
• Symbol Configuration
• Executing the Online Change
• Command ‘Project information’